Detailed descriptions of radio communication networks and systems can be found in literature, such as in Technical Specifications published by, e.g., the 3rd Generation Partnership Project (3GPP). 3GPP Long Term Evolution (LTE) is the fourth-generation radio communication technologies standard developed within the 3rd Generation Partnership Project (3GPP) to improve the Universal Mobile Telecommunication System (UMTS) standard to cope with future requirements in terms of improved services such as higher data rates, improved efficiency, and lowered costs. The Universal Terrestrial Radio Access Network (UTRAN) is the radio access network of a UMTS and Evolved UTRAN (E-UTRAN) is the radio access network of an LTE system. In an UTRAN and an E-UTRAN, a user equipment (UE) is wirelessly connected to a Radio Base Station (RBS) commonly referred to as a NodeB (NB) in UMTS, and as an evolved NodeB (eNodeB or eNB) in LTE. An RBS is a general term for a radio network node capable of transmitting radio signals to a UE and receiving signals transmitted by a UE.
In future generations of radio communication networks, it is foreseen that the number of radio nodes (e.g., RBS:es, radio gateways, relay nodes, etcetera) will increase significantly. Thus, the density of radio nodes will increase. Furthermore, a potentially large number of Machine Type Communication (MTC) devices such as wireless sensors will be introduced. These wireless sensors and similar devices are expected to communicate with the Core Network (CN) via radio nodes. With the introduction of MTC devices in radio communication networks, the potentially large number of MTC devices and the nature of MTC may pose new challenges on the radio communication networks. For example, this new type of communication will have to co-exist with the “classical” communication between UEs (such as mobile phones and tablet computers) and the radio communication network. In such scenario, where the density of not only radio nodes, but also UEs and MTC devices is denser (or much denser) than in previous generations of radio communication networks it will evidently become important that the communication in the radio interface is efficient.